I'm considering going fishing on either Thursday or Saturday morning. Most probably at Harbour Island, mainly as I've seen others fish there.

My questions are:

Bait:
Which bait is best for that area this time of the year? Where can I pump prawn in Strand or Gordon's Bay? I have some Chokka, which I'll definitely give a try. I've seen that rooi aas washes out at Greenways, so I might go check there as well.

Fish:
Which fish can I expect where this time of the year?

Spots:
I'm mainly looking for something simple for now. Still getting used to casting with a multi-reel.

Harbour Island:
Please any tips as to where to throw as I've heard one get's stuck and lose tackle there quite often.

Old Harbour:
I haven't checked out the old Harbour, is that worth it?

Greenways:
I'm also considering the area in front of Greenways, although it seems like you have to go out on the reef, where I'm trying to start off easier.

Strand Fence:
Can one fish past the fence in Strand, since that has been opened and is it worth it?

Any other suggestions for easy fishing? Would be great if it's a kids friendly spot so I can take the kids with.

This time of year you may struggle in that area, but still worth a shot.. in general not the most productive stretch, barring the odd smash somewhere.
Harbour Island a lot of folks fish but not much comes out, late night in the right conditions you may get a good kob.
Old harbour not great, big sea and cast off the wall to the back line of bikini beach some good steamers have come out in the (distant) past. Rocks on other side of bikini by Nun's pool you can give a shot for bankfish / skaamies.
Fence i've not fished the other side, was still closed last time i fished there. But if the structure / water is right i cannot think why it should not produce something, especially near the river mouth if it's open. On the left side it can be a good spot but not lank often, but i did catch my pb kob there funnily enough. Alot can come out there - eagle rays, st. joseph, bellman, odd galjoen against the pipe - reckon they come for the mussels growing on the concrete blocks. But too often the water's full of surfers which is a stuff-up.
Blake's beach is well known but more in summer, especially for elf. Usually a bit of a bellman smash there once a year too. It's a very comfortable spot to fish but small so can get crowded quick. The reefs between it and Greenways - on high you can scratch for kollies and stuff without getting too wet, on low the diehards wade out to the outer reef, stand hip-deep and catch good kob / spotties.
Greenways you can scratch around for bank fish and the odd bossie (small kob). Just past that Harmony Park from in front of the tidal pool for kobbies / flat fish. The reefs to the right - low off the front to deeper water for the same and who knows what else, as it pushes move back/ to the right to work the "gully" as it fills.
Gordon's Bay main beach to the right really good for flat fish but very foul.
Not everywhere is safe, try not fish alone. And be cool with size / bag limits please.